Support Azure Storage Blob (piskvorky#444)

* feat(test): mock azure storage blob classes + unit test them

* feat(azure storage blob): add asb file + update tests

* feat(travis): remove duplicated line

* feat(asb): update tests + implem open function

* feat(tests): add unittests for reading and wrinting class

* feat(tests): fix gzip test

* feat(review): update class names + fix typo

* feat(copyright): update copyright year

* feat(import): use fully qualified name in source

* feat(asb): remove six import

* feat(reader): add __enter__ and __exit__ functions

* feat(import): add try/except on Azure dependencies

* feat(write): handle multiple writings on single files

* feat(feedback): handle PR feedbacks

* feat(feedback): handle PR feedbacks

* feat(feedback): handle PR feedbacks

* feat(feedbacks): handle PR feedbacks

* feat(feedbacks): handle PR feedbacks

* feat(flake8): fix linter requirements + asb requitements in setup.py

* feat(flake8): fix linter requirements + handle python 3.5 syntax

* feat(feedbacks): update string formatting

* feat(coverage): enhance code coverage

* feat(coverage): enhance code coverage

* feat(coverage): enhance code coverage

* feat(flake8): fix linter requirements

Co-authored-by: Nicolas Mitchell <nclsmitchell@MacBook-Pro-de-Nicolas.local>

Author: nclsmitchell

setup.py

@@ -57,13 +57,14 @@ def read(fname):
 
 aws_deps = ['boto', 'boto3']
 gcp_deps = ['google-cloud-storage']
+asb_deps = ['azure-storage-blob', 'azure-common', 'azure-core']
 
-all_deps = install_requires + aws_deps + gcp_deps
+all_deps = install_requires + aws_deps + gcp_deps + asb_deps
 
 setup(
     name='smart_open',
     version=__version__,
-    description='Utils for streaming large files (S3, HDFS, GCS, gzip, bz2...)',
+    description='Utils for streaming large files (S3, HDFS, GCS, ASB, gzip, bz2...)',
     long_description=read('README.rst'),
 
     packages=find_packages(),
@@ -79,7 +80,7 @@ def read(fname):
     url='https://github.com/piskvorky/smart_open',
     download_url='http://pypi.python.org/pypi/smart_open',
 
-    keywords='file streaming, s3, hdfs, gcs',
+    keywords='file streaming, s3, hdfs, gcs, asb',
 
     license='MIT',
     platforms='any',
@@ -93,6 +94,7 @@ def read(fname):
         'test': tests_require,
         'aws': aws_deps,
         'gcp': gcp_deps,
+        'asb': asb_deps,
         'all': all_deps,
     },
     python_requires=">=3.5.*",